10:45 AM - 12:15 PM
[SMP26-P12] Microcrack Clusters in the Plate Boundary Metamorphic Rocks
Keywords:microcrack, fluid flux, metamorphic band
Monomineralic bands constituted mainly with albite and minorly with quartz, epidote, and actinolite are very common in the high-pressure metamorphic basic schists. The matrix between bands is composed of fine-grained actinolite, epidote, chlorite, albite, quartz, and oxides. Bands are commonly about 1mm thickness, and these appear repeatedly by the distance of several mm. The bands are therefore called as the metamorphic bands produced by metamorphic differentiation.
Recently, the author proposed the dissolution-precipitation-fluid flow model of this metamorphic banding in the simple system that contains chlorite, albite, and pore in the basic schist analogue (Toriumi, 2022). The solution containing ionic species constituting minerals above is assumed to flows across the incipient bands with high angle in the simulation. In this fluid flow system, the simulation results clearly show the formation of the monomineralic bands and pore band. It is important that the banding orientation becomes vertical to the fluid flow in the simulation, thereby showing that the regional fluid flow of solution nearly saturated with metamorphic minerals such as albite and chlorite is vertical to the schistosity plane because of metamorphic bands are almost always parallel to the schistosity in the plate boundary metamorphic belt.
Therefore, it is suggested that the regional metamorphic schists are suffered from the solution flow across the schistosity plane, being inconsistent with the common sense of the metamorphic petrologists that is the chemical homogeneity along the schistosity plane and fluid flow should be along the schistosity plane.
However, it should be considered that the finite deformation configuration of the metamorphic schists is represented by the shortening axis normal to the schistosity plane and elongation axis parallel to the schistosity plane, thereby showing the instantaneous growth and propagation of open cracks normal to the schistosity plane. It should be suggested that the fluid flow in the schists may be normal to the schistosity plane and metamorphic bands as suggested previously by the author.
In this paper, the author intends to show many signatures that the orientation of the dominant metamorphic fluid flow was normal to the schistosity plane and the metamorphic bands of the basic schists. The important texture related to the fluid flow during the metamorphism is the microcrack clusters elongated normal to the schistosity sealed by chlorite, actinolite, albite, and quartz.
ref. Toriumi, M., 2022, Geochemical Mechanics and Deep Nueral Network Modeling, Springer.
Recently, the author proposed the dissolution-precipitation-fluid flow model of this metamorphic banding in the simple system that contains chlorite, albite, and pore in the basic schist analogue (Toriumi, 2022). The solution containing ionic species constituting minerals above is assumed to flows across the incipient bands with high angle in the simulation. In this fluid flow system, the simulation results clearly show the formation of the monomineralic bands and pore band. It is important that the banding orientation becomes vertical to the fluid flow in the simulation, thereby showing that the regional fluid flow of solution nearly saturated with metamorphic minerals such as albite and chlorite is vertical to the schistosity plane because of metamorphic bands are almost always parallel to the schistosity in the plate boundary metamorphic belt.
Therefore, it is suggested that the regional metamorphic schists are suffered from the solution flow across the schistosity plane, being inconsistent with the common sense of the metamorphic petrologists that is the chemical homogeneity along the schistosity plane and fluid flow should be along the schistosity plane.
However, it should be considered that the finite deformation configuration of the metamorphic schists is represented by the shortening axis normal to the schistosity plane and elongation axis parallel to the schistosity plane, thereby showing the instantaneous growth and propagation of open cracks normal to the schistosity plane. It should be suggested that the fluid flow in the schists may be normal to the schistosity plane and metamorphic bands as suggested previously by the author.
In this paper, the author intends to show many signatures that the orientation of the dominant metamorphic fluid flow was normal to the schistosity plane and the metamorphic bands of the basic schists. The important texture related to the fluid flow during the metamorphism is the microcrack clusters elongated normal to the schistosity sealed by chlorite, actinolite, albite, and quartz.
ref. Toriumi, M., 2022, Geochemical Mechanics and Deep Nueral Network Modeling, Springer.